1. Field of the Invention
The present invention relates generally to fluid flow control devices for controlling the flow of fluid along fluid flow pathways. More particularly, the invention concerns a highly novel fluid flow control device that delivers a substantially constant output flow rate from a micro-fluidic system under conditions of fluctuating or otherwise varying temperature and pressure by lining the fluid flow pathway with vanes, weirs, fibers or whiskers that move further into the channel as the pressure of the fluid flowing through the fluid flow pathway increases.
2. Discussion of the Prior Art
Various types of fluid flow control devices have been suggested in the past. Typically, these prior art devices use flow regulators, valves, diaphragms and like constructions all employing moving parts to achieve flow rate stabilization. Such constructions tend to be complex, costly and often of questionable reliability, particularly when used in medical applications.
Exemplary of a prior art flow regulator that embodies a deflectable beam placed within the fluid flow path is that described in U.S. Pat. No. 5,163,920 issued to Olive. This patent discloses a flow regulator-restrictor that is placed in a fluid path to passively compensate for variations in fluid pressure by deflection or movement. In one form of the Olive invention a silicon micro-machined housing has a damper beam cantilevered to the interior wall between the inlet and outlet. Deflections of the beam vary the volume of the restrictive gap between the damper beam and the internal walls of the housing and adjacent the outlet.
U.S. Pat. No. 3,438,389 issued to Lupin describes a flow metering orifice with automatic compensation for change in viscosity. Compensation for changes in viscosity in the Lupin device is effected by a movable valve element that shifts to increase the effective flow area as the viscosity of the fluid increases and to decrease the effective flow when the viscosity decreases.
The thrust of the present invention is to provide a highly novel flow control device that is of simple construction and design and is significantly more reliable than prior art flow control devices of conventional design. More particularly, the device of the present invention delivers a substantially constant output flow rate from a micro-fluidic system under conditions of fluctuating or otherwise varying temperature and pressure by lining the fluid flow pathway with vanes, fibers, whiskers or weirs that move further into the channel in response to an increase in the pressure of the fluid flowing through the fluid flow pathway and retreats toward the wall as the pressure decreases.
With the foregoing in mind, it is apparent that the method of flow rate control contemplated by the present invention is fundamentally different in character from the prior art flow rate regulators. Advantageously, because the simple construction of the devices of the present invention, their manufacture is substantially easier and less expensive than conventional prior art flow rate stabilization devices.
An example of one form of a flow rate control system contemplated by present invention comprises a device having one or more flexible vanes protruding from one wall of an otherwise straight channel that move further into the channel as the pressure driving the fluid flowing through the fluid flow pathway increases. Advantageously, this type of vane structure is quite easy to incorporate into a fluidic chip in which the vane or vanes are merely an especially molded or grown feature protruding from the walls of the fluid flow channel.